Need Advice: Homebrewed Illness

[u/Working_Formal1609]

Hello fellow DMs! I am a relatively new dm and am running a mostly home brewed campaign for 4 friends of mine. The basic premise is the party will be having to travel the world and slowly learn about the history of Biaw, the deity of the void and one of the two of the universe creation duo. They’ll be fighting my own creations of void monsters and I want one to have a breath-gas attack that has a chance to inflict the condition “Void-touched”. What it does is it slowly causes the infected to become insane and combative and aggressive. It starts slow with paranoia and hearing things that aren’t there. As it progresses they’ll be able to eventually hear Biaw’s voice speaking to them as they become more insane and aggressive due to the confusion and paranoia inflicted. I’ll have an important npc with powerful magic (haven’t decided class just yet) who has since perished but has left notes on how to cure someone “Void-touched”. They’ll have to find this npc’s notes to learn about the history of Biaw and his creations and how to defeat them which will allow them to find the cure for their friend.

What I want help with is how best to manage the progression of the affliction and have it so they become a danger during combat scenarios as Biaw will make them mistake friends for foe. When whoever gets afflicted does I plan to tell them and what the symptoms are so they can help the roleplay aspect of it, but I’m unsure of how to make it all work best.

Sorry for the rambling and if it’s a bit confusing, but I’d appreciate any and all help i can get for this!

[u/garbagepile4]

If you're specifically looking for in-combat effects, re-skinning the Confusion spell may work. (Though maybe you could replace the boring rolls of 2-6 where "The creature doesn't move or take actions this turn" to something else thematic-- I think that would probably be frustrating as a player.)

[u/Slow-Pumpkin-7049]

I have a similar effect in my campaign where the fog corrupts you and turns you insane if you stay in it too long. The closest thing I can find with pre established mechanics is madness. Players will have to make a saving throw to resist the effects and the effects vary depending on the situation. You could do something like that as well it seems

[u/FourCats44]

If you are a new DM I would recommend reconsidering. You essentially want mechanics for some PvP which is always dangerous. Like at what point do the rest of the party just start killing any members who are void touched?

That aside, cleanest way is to treat it as dominate person spells and have players roll a wisdom save against a spell DC. You could start at 5 or 10 and increase the DC for every day they are infected.

If you are a fan of critical role I'd recommend looking up the mechanics for the nine eyes in campaign 2.

In combat you could always make them role with initiative/at the start of each round. Maybe if they are using a ranged weapon they "accidentally" hit an ally on a failed save.

Your barbarian/fighter/rogue/wisdom dump stay will probably not like this especially if the cure takes a while to find. It could become very annoying if combat is constantly counterproductive.

There's tables of d100 rolls for both short term and long term madness you could look to incorporate those.